Personally, I think that it's because of N3DS that the release takes time (they surely want to release all in 1-time), remember when they said that there won't be EmuNAND on it :

New3DS NATIVE_FIRM

The ARM9-loader has added a new keyX with keyslot 0x16 that is generated on hard-boot. The ARM9 binary is now encrypted with this key. In order to decrypt it, you'll need arm9hax on firm > 9.4, or some form of bootromhax.

We will not be able to support emunand 9.5 or higher for a while on the New 3DS. This is only an issue for the New 3DS, the old 3DS and 2DS will never have this issue

If your on gateway your likely using CIAs for all your updates and DLC needs. Considering online play is still possible on lower firmwares what is the big concern about not being able to update to the latest firmware right away? I can understand if you hadn't updated off of 9.0 yet but Id venture to say most people have already. In any case just be patient Gateway is consistent and it will be out soon

yeah seems like. See 3.0. It seems they wanted release new 3ds and old 3d support in one update, but it tooks to long time, so they pushed(after months) the 3.0 update. Then with 3.1 New 3ds support come.

yeah seems like. See 3.0. It seems they wanted release new 3ds and old 3d support in one update, but it tooks to long time, so they pushed(after months) the 3.0 update. Then with 3.1 New 3ds support come.